In general, in image forming devices such as laser printers and digital copiers, a laser beam is applied to a photoconductive member to correspond to data on an image to be printed, thereby forming an electrostatic latent image on the photoconductive member. In the devices, a toner image is formed by supplying a toner to the electrostatic latent image and the toner image is transferred to a sheet and then thermally fixed.
The toner for forming a toner image is generally contained in a cartridge. However, when an erroneous cartridge is attached to the image forming device, a toner image cannot be formed properly, and the image forming device may be damaged. Therefore, in order to prevent the attachment of an erroneous cartridge, a correct cartridge is configured so that a cartridge engaging portion is formed in a cartridge frame so as to normally engage with a main-body engaging portion formed in the image forming device.
A memory device may be attached to the cartridge, for storing information useful for easy replacement or maintenance of a cartridge at a proper time, such as an amount of toner or the number of printable sheets. From the viewpoint of performance or request for a decrease in cost, a contact IC chip may be used as the memory device.
A controller is disposed in the image forming device. In this case, a main-body terminal is provided to electrically connect with the controller, and a cartridge terminal is provided to electrically connect with the memory device. By bringing the main-body terminal and the cartridge terminal into contact with each other, the controller of the image forming device can read the information stored in the memory device to perform a proper control operation. In order to allow the memory device to operate normally, the cartridge terminal and the main-body terminal are necessarily in stable contact with each other. Therefore, for example, JP-A-2003-177650 discloses a mechanism for bringing an electrical contact of the memory device provided on a process cartridge and an electrical contact of the image forming device into contact with each other by attaching the process cartridge to the image forming device and closing an opening and closing cover.
In the above cartridge, since a cartridge engaging portion is disposed on one side of an end portion of the cartridge and a terminal of the memory device is disposed on the other side, the cartridge increases in size and a space in the image forming device for receiving the cartridge increases in size, thereby causing an increase in size of the entire device.
In addition, it is necessary to provide the image forming device with a main-body engaging portion corresponding to the cartridge engaging portion and a main-body terminal corresponding to the cartridge terminal, thereby making the configurations of the cartridge and the image forming device complicated.